import random
checkcode = ''
for i in range(4):
    current = random.randrange(0,4)
    current == i
    ran=random.randint(65,122)
    if 65<=ran<=90 or 97<=ran<=122:
        tep = chr(ran)
    else:
        ran=random.randint(65,122)
    checkcode+=str(tep)
print(checkcode)
